The invention relates to a suction air filter for combustion engines.
From U.S. Pat. No. 4,006 000, an air filter is known with an essentially cylindrical housing which has a fresh air inlet (intake), which is arranged tangentially along the housing. A filter insert is located in this housing and air flows radially through the filter. The housing itself can be connected by a bayonet lock with a cylindrical suction air collector. A safety cartridge is located inside this suction air collector to prevent the penetration of dirt and dust into the suction air connecting piece during a change of the filter insert.
A seal is formed between the safety cartridge and the filter insert because after locking the bayonet lock, the filter insert is axially displaced in the direction of the safety cartridge and the face of the filter insert comes to rest on the face of the safety cartridge. This axial displacement is undertaken with the aid of a setting screw arranged on the face, which axially moves the end disk of the filter insert. Simultaneously, through this axial bracing, the bayonet lock is locked.
A disadvantage of the known filter arrangement is that during exchange of a filter insert, several bracing devices must be released. Furthermore, the release of this bracing device, as well as the fastening, must be carried out in accordance with a certain sequence.
If this sequence is not precisely observed, i.e., if during placement of a filter insert, the filter insert is moved at first towards the front by means of the setting screw and subsequently the bayonet lock is operated, then this leads invariably to a destruction of the axial seal of the filter insert, and thus to the leakage of air into the pure air chamber.
In addition to the cumbersome handling, the known filter arrangement also requires, due to the arrangement of the setting screw, much room for installation purposes, which in most cases of application is extremely limited.
Furthermore, from DE-GM 14 76 531, an air filter is known in which the entire housing is pushed onto a suction connection and is attached to same with a bayonet lock.
However, the disadvantage of this type of attachment is that vibrations and shocks of the vehicle, which is fitted with the known air filter, lead to a situation wherein the bayonet lock becomes loosebout a rotational point 43 and is rigid connection, leads to uncontrolled movements of the air filter.
Furthermore, from DE-OS 39 06 550, a liquid filter is known in which a cup-like housing is attached to a lid with a tension strip. Such a tension strip band is capable, in the case of relatively small liquid filters, such as gasoline filters, of tightly connecting the housing to the lid. However, in the case of large-volume air filters, the axial force component produced by the tension band does not suffice for ensuring a seal of the air filter insert located inside the air filter housing.